Subversion Repositories DashDisplay

Rev

Rev 28 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  1. /* ----------------------------------------------------------------------    
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  3. *    
  4. * $Date:        19. March 2015
  5. * $Revision:    V.1.4.5
  6. *    
  7. * Project:          CMSIS DSP Library    
  8. * Title:                arm_sin_cos_f32.c    
  9. *    
  10. * Description:  Sine and Cosine calculation for floating-point values.  
  11. *    
  12. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13. *  
  14. * Redistribution and use in source and binary forms, with or without
  15. * modification, are permitted provided that the following conditions
  16. * are met:
  17. *   - Redistributions of source code must retain the above copyright
  18. *     notice, this list of conditions and the following disclaimer.
  19. *   - Redistributions in binary form must reproduce the above copyright
  20. *     notice, this list of conditions and the following disclaimer in
  21. *     the documentation and/or other materials provided with the
  22. *     distribution.
  23. *   - Neither the name of ARM LIMITED nor the names of its contributors
  24. *     may be used to endorse or promote products derived from this
  25. *     software without specific prior written permission.
  26. *
  27. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38. * POSSIBILITY OF SUCH DAMAGE.  
  39. * -------------------------------------------------------------------- */
  40.  
  41. #include "arm_math.h"
  42. #include "arm_common_tables.h"
  43.  
  44. /**    
  45.  * @ingroup groupController    
  46.  */
  47.  
  48. /**    
  49.  * @defgroup SinCos Sine Cosine  
  50.  *    
  51.  * Computes the trigonometric sine and cosine values using a combination of table lookup  
  52.  * and linear interpolation.    
  53.  * There are separate functions for Q31 and floating-point data types.  
  54.  * The input to the floating-point version is in degrees while the  
  55.  * fixed-point Q31 have a scaled input with the range  
  56.  * [-1 0.9999] mapping to [-180 +180] degrees.  
  57.  *
  58.  * The floating point function also allows values that are out of the usual range. When this happens, the function will
  59.  * take extra time to adjust the input value to the range of [-180 180].
  60.  *  
  61.  * The implementation is based on table lookup using 360 values together with linear interpolation.  
  62.  * The steps used are:  
  63.  *  -# Calculation of the nearest integer table index.  
  64.  *  -# Compute the fractional portion (fract) of the input.  
  65.  *  -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1.      
  66.  *  -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>.    
  67.  *  -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1.      
  68.  *  -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>.    
  69.  */
  70.  
  71.  /**    
  72.  * @addtogroup SinCos    
  73.  * @{    
  74.  */
  75.  
  76. /**    
  77.  * @brief  Floating-point sin_cos function.  
  78.  * @param[in]  theta    input value in degrees    
  79.  * @param[out] *pSinVal points to the processed sine output.    
  80.  * @param[out] *pCosVal points to the processed cos output.    
  81.  * @return none.  
  82.  */
  83.  
  84. void arm_sin_cos_f32(
  85.   float32_t theta,
  86.   float32_t * pSinVal,
  87.   float32_t * pCosVal)
  88. {
  89.   float32_t fract, in;                             /* Temporary variables for input, output */
  90.   uint16_t indexS, indexC;                         /* Index variable */
  91.   float32_t f1, f2, d1, d2;                        /* Two nearest output values */
  92.   int32_t n;
  93.   float32_t findex, Dn, Df, temp;
  94.  
  95.   /* input x is in degrees */
  96.   /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */
  97.   in = theta * 0.00277777777778f;
  98.  
  99.   /* Calculation of floor value of input */
  100.   n = (int32_t) in;
  101.  
  102.   /* Make negative values towards -infinity */
  103.   if(in < 0.0f)
  104.   {
  105.     n--;
  106.   }
  107.   /* Map input value to [0 1] */
  108.   in = in - (float32_t) n;
  109.  
  110.   /* Calculation of index of the table */
  111.   findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
  112.   indexS = ((uint16_t)findex) & 0x1ff;
  113.   indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
  114.  
  115.   /* fractional value calculation */
  116.   fract = findex - (float32_t) indexS;
  117.  
  118.   /* Read two nearest values of input value from the cos & sin tables */
  119.   f1 = sinTable_f32[indexC+0];
  120.   f2 = sinTable_f32[indexC+1];
  121.   d1 = -sinTable_f32[indexS+0];
  122.   d2 = -sinTable_f32[indexS+1];
  123.  
  124.   Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE
  125.   Df = f2 - f1; // delta between the values of the functions
  126.   temp = Dn*(d1 + d2) - 2*Df;
  127.   temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
  128.   temp = fract*temp + d1*Dn;
  129.  
  130.   /* Calculation of cosine value */
  131.   *pCosVal = fract*temp + f1;
  132.  
  133.   /* Read two nearest values of input value from the cos & sin tables */
  134.   f1 = sinTable_f32[indexS+0];
  135.   f2 = sinTable_f32[indexS+1];
  136.   d1 = sinTable_f32[indexC+0];
  137.   d2 = sinTable_f32[indexC+1];
  138.  
  139.   Df = f2 - f1; // delta between the values of the functions
  140.   temp = Dn*(d1 + d2) - 2*Df;
  141.   temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
  142.   temp = fract*temp + d1*Dn;
  143.  
  144.   /* Calculation of sine value */
  145.   *pSinVal = fract*temp + f1;
  146. }
  147. /**    
  148.  * @} end of SinCos group    
  149.  */
  150.